Radio tuning apparatus

ABSTRACT

Radio tuning apparatus of the pushbutton type in which a plurality of variable impedance devices may be adjusted by use of a carriage bar drivingly associated with rods extending from said devices. The carriage bar is provided with an elongated strip of resilient material within which the drive rods are frictionally received.

United States Patent Alvin E. Thompson North Wales, Pa.

Nov. 6, 1970 Dec. 28, 1971 Philco-Ford Corporation Philadelphia, Pa.

Inventor Appl. No. Filed Patented Assignee RADIO TUNING APPARATUS 2 Claims, 4 Drawing Figs.

11.8. C1 Int. Cl Field 01 Search...

336/131 l-l0lf2l/06 336/130, 131;338/l30, 131; 174/65 G, 60, 151

References Cited UNITED STATES PATENTS 2/1951 Kolks 336/131 8/1970 Phillips, Jr 174/65 G X 3/1934 Webb et a1 174/151 9/1960 I-Iasselhom l 74/ 60 Primary Examiner-Thomas J. Kozma AttorneyCarl I-I. Synnestvedt ABSTRACT: Radio tuning apparatus of the pushbutton type in which a plurality of variable impedance devices may be adjusted by use of a carriage bar drivingly associated with rods extending from said devices. The carriage bar is provided with an elongated strip of resilient material within which the drive rods are frictionally received.

RADIO TUNING APPARATUS BACKGROUND OF THE INVENTION My invention is useful in radio equipment of the kind in which a plurality of variable impedance devices are tuned or adjusted simultaneously through the agency of a single, rectilinearly movable carriage. While of broader applicability the invention is especially useful in pushbutton operated automobile radios. In tuners for such radios it is common to utilize a plurality of variable impedance devices, for example tunable inductances each comprising a coil and a core. In such devices it is customary for the core to be movable rectilinearly to adjust the frequency of the tuner. To provide such rectilinear movements each core has a stem or rod drivingly associated therewith, and a core bar or carriage spans said rods and is movable in a direction to reciprocate said rods having parallel paths. The core bar has commonly been provided with a plurality of grommets, usually of rubber, within which the rods are frictionally received.

Substantial problems have arisen during the manufacture of such known apparatus because of the fact that the rubber grommets are often inadvertently pushed out of their place in the core bar, by the assembler, during insertion of the core rod. To prevent rotation of the grommet when the threaded stem of the core rod is rotated for adjustment purposes, both the grommet and the core bar aperture generally have been of square configuration. Replacement of the grommets within the small square apertures provided in the core bar has proven to be a very troublesome task. Consequently, when a grommet is displaced, it is common to remove the tuning unit from the assembly line for rework. After the grommets have been forced back into the core bar apertures, the tuning unit is returned to assembly. These difficulties have considerably increased the amount of handwork, and consequent cost, which is involved in the manufacture of such tuners.

SUMMARY AND OBJECTIVES OF THE INVENTION My invention completely eliminates the aforesaid problems by the simple expedient of providing the core bar with a con tinuous strip of resilient material, for example rubber, which strip is provided with holes molded or pierced therein and disposed to conform to apertures provided in the core bar. With such a construction, the problem of displacement of parts during assembly is eliminated, and it is the general object of the invention to accomplish this purpose by provision of a simplified and inexpensive core bar which is well adapted to tuner manufacture by automatic machinery.

In accordance with one aspect of the invention, it is contemplated that the core bar be channel-shaped in cross section and that the rubber strip be pierced after it has been inserted in the channel. In such an embodiment the rubber can be clamped by closing the channel during the piercing operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective, approximately full size, illustration showing the core bar and certain associated elements of a pushbutton tuning device;

FIG. 2 illustrates the grommet arrangement utilized in the prior art;

FIG. 3 shows the channel-shaped configuration of my improved core bar, and the manner in which the resilient strip may be clamped therein; and

FIG. 4 is a detailed sectional view looking in the direction of the line 4-4 applied to FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates, from the rear, the forward wall of a pushbutton tuning device particularly useful in automobiles. The drawing illustrates only those portions of the tuner which are essential to an understanding of the invention. Through apertures 11 in the forward wall 10 there extend a plurality of pushbutton or key assemblies, one of which is shown at 12. It

will be understood that these assemblies extend through the slots or apertures 11 provided in the wall 10, and that each has a finger-operable button or extension (not illustrated) which projects from the front wall 10, that is, toward the left as viewed in FIG. I. In accordance with known practice each key assembly carries a cam 13 which is adapted to contact and position a treadle bar 14, the latter being comprised of upper and lower bars 14a and 14b carried by a pair of end frames I5-l5 each pivoted in one of pair of space, opposed, sidewalls l6-l6, which latter extend rearwardly from the front wall 10. Each end frame 15 of the treadle bar has a lever- Iike extension 17 which, as is conventional, extends upwardly and drives the core bar 19 through pins shown at 18 and pro- 1 5 jecting through drive extensions 20 and 21, which form part of the generally C-shaped core bar or carriage 19. The sidewalls 16 are slotted, as shown at 22, and core bar 19 is free to move rectilinearly within the slots and hence to drive the cores to positions determined by the pivotal movement imparted to the treadle bar 14 by cam 13. The construction, as thus far described, is of well-known type and requires no further description herein.

The core bar 19 is adapted to adjust, or tune, a plurality of variable impedance devices. In the present embodiment these devices are of the variable inductance type and comprise coils, one of which is shown schematically at 23, and cores 24 longitudinally reciprocable within the coils. Each core is provided with a rod or stem 25 adapted to be secured in driven engagement with the core bar 19. One of the cores is shown, in FIGS. 1 and 4, engaged with the core bar 19. The others (FIG. I) are shown prior to association with the bar.

In particular accordance with the present invention, the center portion of the core bar is channel-shaped in cross section and a strip of rubber or other resilient material 26 is disposed within the channel, being secured between channel walls 27 and 28, as shown in FIGS. 3 and 4. Unlike the prior art arrangement shown in FIG. 2, in which individual grommets G of square configuration are forced through square apertures provided in an angle-shaped core bar C, I provide the rubber strip 26 and external the same substantially throughout the length of the channel (see FIG. I). It is retained therein in such manner as to prevent any possibility of displacement during assembly of the cores 24 with the bar 19. The walls 27 and 28 which define the channel are provided with aligned apertures 29, 30 through which extend the core rods or stems 25, in the manner shown in FIGS. 1 and 4. To

accommodate such disposition of the rods, the strip 26 is apertured. Most conveniently this is done by piercing, as referred to below. The piercing establishes an interaperture distance equal to the spacing between the core bars.

As will be apparent from inspection of the three cores which are shown in FIG. 1 prior to association with the core bar 19, the free end of each drive rod or stem 25 is externally threaded as shown at 31 to provide for frictional retention of the rod within the strip 26.

It is desirable that the walls 27, 28 which define the channel by spread sufficiently (FIG. 3) to accommodate ready insertion of the strip 26, after which one wall, for example the wall 28, may be forced toward the opposite wall until it occupies the position shown in FIG. 4 and clamps the strip 26 securely in position. In the broader aspect of the invention the strip may, of course, be secured to the core bar by other means.

During assembly of the apparatus it is very simple to guide the core rods 25 into and through the apertures 32 (FIG. 3) which have been provided in the strip. There is no possibility of dislodgement of the latter during this operation.

The strip may comprise a molded piece formed with the apertures 32 therein. However, in preferred practice, holes are pierced in the rubber, or other material of the strip, after assembly of the strip and core bar, and during closing of the channel.

Iclaim:

1. In combination with pushbutton radio tuning apparatus of the kind having a plurality of variable inductance tuning devices, each comprising a coil and a core rectilinearly movable with respect to the coil and each core having a rod drivingly associated therewith, carriage means for moving said rods rectilinearly and along parallel paths, said carriage means comprising: a core bar extending in a direction perpendicular to the path of movement of the cores and being mounted for sliding movement in the direction of said path of movement, said core bar being substantially U-shaped in cross section and provided, in the leg portions of the U, with aligned apertures arranged in confronting pairs and through which extend said rods; and a strip of resilient rubber or the like frictionally clamped within the channel and having portions confronting said aligned apertures, said strip extending therethrough a plurality of individual apertures of circular cross section and of a size frictionally to retain said rods, each said rod passing through a pair of said aligned core bar apertures and through a corresponding one of the individual apertures provided in said strip of material, said rod being frictionally retained within said strip and thus maintained in driven association with said core bar.

2. The combination in accordance with claim 1, in which said individual apertures in said strip of material are of a diameter smaller than the diameter of the rods which pass therethrough, and each rod is externally threaded to increase the friction and to provide for positional adjustment of the cores with respect to their associated coils.

PO-w e UNITED STATES PATENT ()FFICE I CERTIFICATE OF CORRECTION Patent: No. 3,631 368 Dated December 28, 1971 Inventor) ALVIN E. THOMPSON, Assignor to PHILCO-FORD CORPORATION It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2 line 9, the word a should be inserted before pair"; v I

7 line #0, "external" should read extend 5 line 58, "by" should be be Column 3, line 13, bhe word "strip should be followed by having v I Signed and sealed this 13th day of June 1972.

(SEAL) Attest:

v EDWARD M.FLETCHER, J'R. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents W105) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,631,368 Dated December 28, 1971 Inventor) ALVIN E. THOMPSON, Assignor to PHILCO-FORD CORPORATION It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

r" I .1 Column 2, line 9, the word a should be inserted before "pair";

line L0, external" should read extend 5 line 58, "by" should be be Column 3, line 13, the word "strip should be followed by having Signed and sealed this 13th day of June 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSGHALK Attesting Officer Commissioner of Patents 

1. In combination with pushbutton radio tuning apparatus of the kind having a plurality of variable inductance tuning devices, each comprising a coil and a core rectilinearly movable with respect to the coil and each core having a rod drivingly associated therewith, carriage means for moving said rods rectilinearly and along parallel paths, said carriage means comprising: a core bar extending in a direction perpendicular to the path of movement of the cores and being mounted for sliding movement in the direction of said path of movement, said core bar being substantially U-shaped in cross section and provided, in the leg portions of the U, with aligned apertures arranged in confronting pairs and through which extend said rods; and a strip of resilient rubber or the like frictionally clamped within the channel and having portions confronting said aligned apertures, said strip extending therethrough a plurality of individual apertures of circular cross section and of a size frictionally to retain said rods, each said rod passing through a pair of said aligned core bar apertures and through a corresponding one of the individual apertures provided in said strip of material, said rod being frictionally retained within said strip and thus maintained in driven association with said core bar.
 2. The combination in accordance with claim 1, in which said individual apertures in said strip of material are of a diameter smaller than the diameter of the rods which pass therethrough, and each rod is externally threaded to increase the friction and to provide for positional adjustment of the cores with respect to their associated coils. 